1. Field of the Invention
The present invention relates to a control system of a hydraulic pressure control valve.
2. Description of Related Art
There has been conventionally known a hydraulic pressure control valve including a spool that moves in a sleeve (for example, see Japanese Patent Application Publication No. 2012-31741 (JP 2012-31741 A)). The hydraulic pressure control valve is provided with a return spring for biasing the spool to one side, and an electromagnetic solenoid for driving the spool to the other side. The hydraulic pressure control valve is configured such that its hydraulic pressure is controlled by the spool being moved in the sleeve according to a current supplied to the electromagnetic solenoid.
Here, in such a hydraulic pressure control valve, foreign matter mixed in oil may be stuck on the spool. When the foreign matter is stuck on the spool as such, the spool malfunctions, which makes it difficult to control the hydraulic pressure appropriately. In view of this, in the hydraulic pressure control valve of JP 2012-31741 A, when foreign matter is stuck, the spool is forcibly reciprocated, so as to remove the foreign matter thus stuck. Note that the reciprocation of the spool is performed so that the spool comes and goes repeatedly between one end and the other end of the sleeve so as to crush the foreign matter.
However, in such a conventional hydraulic pressure control valve, it is possible to remove foreign matter that can be crushed, but it is difficult to remove foreign matter that cannot be crushed.